The present invention relates to an angle adjusting device for adjusting a tilting angle of a backrest portion of a legless chair or a foldable bed, for example.
In an easy-to-carry foldable bed folded into three by folding down the backrest portion and footrest portion over the seat portion, for example, each of the frames respectively forming the backrest portion and footrest portion is coupled to the frame of the seat portion through an angle adjusting device, whereby it is possible to adjust tilting angles of the backrest portion and footrest portion with respect to the seat portion.
As is disclosed in Japanese Utility Model Publication No. 59-20118 filed by the inventors of the present application, for example, such an angle adjusting device is provided with coupling portions each coupled to the respective tip end portions of the two frames respectively forming, for example, the seat portion and backrest portion.
The coupling portion at the seat portion side commonly used as the stationary side is provided with a pair of disc portions with their thickness direction directed to the width direction of the foldable bed, and the coupling portion at the backrest portion side commonly used as the movable side coaxially supports a spur ratchet gear placed with its thickness direction directed to the width direction of the foldable bed.
Also, a hook of ratchet supported somewhere between the pair of disc portions is allowed to move around the axis in the width direction of the foldable bed, and pushed by a spring in a direction such that the ratchet engages with the gear teeth of a ratchet gear.
Each of the gear teeth has a tapered surface such that presses the ratchet against the spring in association with a rotation of the ratchet gear when the backrest portion is folded, so that the engagement with the ratchet can be released. However, once the ratchet reaches the adjacent gear tooth, the ratchet constantly pushed by the spring engages with that gear tooth again. Also, each of the gear teeth has a surface of a shape such that maintains the engagement with the ratchet in association with a rotation of the ratchet gear when the backrest portion is unfolded.
Hence, a tilting angle of the backrest portion can be changed as one desires in the folding direction, whereas the tilting angle of the backrest portion in the unfolding direction with respect to the seat portion can be changed step by step in accordance with the gear teeth because the ratchet is locked.
Here, the angle adjusting device as discussed above is provided with releasing mechanism that releases the engagement between the ratchet and gear teeth by pressing the ratchet against the spring when a tilting angle of the backrest portion in the folding direction reaches a predetermined angle. The releasing mechanism returns the ratchet and gear teeth in the initial engagement state when the backrest portion is rotated to the maximum unfolded position after the engagement is released.
However, the conventional angle adjusting device as discussed above maintains the backrest portion, for example, of the foldable bed, at a predetermined angle by engaging the ratchet with a single gear tooth of the ratchet gear, which raises a problem that, when one lies down on the foldable bed, all the applied load concentrates onto the single gear tooth and ratchet.
The above problem may be solved by upsizing the gear teeth and ratchet. However, this solution causes inconveniences such that the entire angle adjusting device becomes so large that it impairs one""s lying comfort, etc. Also, when the gear teeth alone are upsized while maintaining the size of the entire angle adjusting device intact, the total number of the teeth is reduced, which raises another problem that an adjustable angle per step becomes larger.
It may be possible to increase hardness of the gear teeth and ratchet without changing their respective sizes by subjecting the same to carburization or making the same out of materials having higher hardness. However, this increases the manufacturing costs, which poses another problem.
The present invention is devised to solve the above problems and has an object to provide a rigid angle adjusting r, which can be assembled at a low cost without increasing the size by providing a plurality of engaging portions to a pair of rotors that relatively rotate around the axis of rotation on their respective counter surfaces opposing in a direction along the axis of rotation, and pushing the rotors in an opposing direction by a spring so as to maintain the engagement of the engaging portions on the rotors.
An angle adjusting device of the present invention is an angle adjusting device capable of adjusting a relative rotating position of a pair of rotors coupled through an axis of rotation step by step, the device including: a plurality of engaging portions provided on surfaces of the pair of rotors opposing in a direction along the axis of rotation; and a spring for pushing the pair of rotors in an opposing direction.
According to the invention, it is arranged such that a plurality of engaging portions are provided to a pair of rotors that relatively rotate around the axis of rotation on their respective counter surfaces opposing in a direction along the axis of rotation, and a spring for pushing the rotors in an opposing direction is provided to maintain the engagement between the rotors. Consequently, it is possible to readily assemble a rigid and compact angle adjusting device that develops a quite large engaging strength by engaging at the plurality of engaging portions.
The angle adjusting device of the present invention can be attached to a foldable bed, a legless chair, etc. as discussed above through coupling portions that will be described below. It should be appreciated, however, that the application is not limited to the foldable bed, legless chair, etc., and the angle adjusting device can be employed in other products that need angle adjustment. Also, the angle adjusting device does not have to be attached to the foldable bed, legless chair, etc. through the coupling portion, and can be attached to the same at the rotors either directly or indirectly.
Another angle adjusting device of the present invention is characterized by further including a releasing body placed concentrically somewhere between the pair of rotors, wherein the releasing body allows engagement between the pair of rotors when placed at a first rotating position with respect to either one of the pair of rotors, and releases the engagement by moving the pair of rotors apart from each other when placed at a second rotating position.
According to the invention, it is arranged such that a releasing body is placed concentrically somewhere between the pair of rotors, and the releasing body allows engagement between the pair of rotors when placed at the first rotating position with respect to either one of the pair of rotors, and releases the engagement by moving the pair of rotors apart from each other when placed at the second rotating position. Consequently, it is possible to provide releasing mechanism for the engagement of the angle adjusting device as discussed above by a simple arrangement.
Still another angle adjusting device of the present invention is characterized in that: one of the either one of the rotors and the releasing body is provided with a convex portion on a counter surface opposing the other; and the other is provided with, on a counter surface opposing a counterpart, a concave portion that engages with the convex portion when the releasing body is placed at the first rotating position, the convex portion moving one of the either one of the rotors and the releasing body apart from the other by touching the counter surface of the other except for the concave portion when the releasing body is placed at the second rotating position.
According to the invention, it is arranged such that one of the either one of the rotors and the releasing body is provided with a convex portion on a counter surface opposing the other, and the other is provided with, on a counter surface opposing a counterpart, a concave portion that engages with the convex portion when the releasing body is placed at the first rotating position, the convex portion moving one of the either one of the rotors and the releasing body apart from the other by touching the counter surface of the other except for the concave portion when the releasing body is placed at the second rotating position. Consequently, when the releasing body is at the first rotating position, the convex portion fits into the concave portion and the releasing body is in a state described as, for example, closely adhering to the either one of the rotors, whereby the pair of rotors engage with each other. On the other hand, when the releasing body is at the second rotating position, the convex portion touches the counter surface of the other except for the concave portion, whereby the either one of the rotors and the releasing body that have been in the above closely adhering state are moved apart relatively from each other. Consequently, the either one of the rotors and the other rotor are spaced apart from each other, thereby making it possible to release the engagement as discussed above.
Still another angle adjusting device of the present invention is characterized in that the releasing body is provided with two contact portions spaced apart by a predetermined distance in a direction of a relative rotation with respect to the other rotor, and the other rotor is provided with a moving portion that moves between the two contact portions in association with a relative rotation with respect to the releasing body, the moving portion allowing the releasing body to rotate to the first and second rotating positions with respect to the either one of the rotors by touching the two contact portions, respectively.
According to the invention, it is arranged such that the releasing body is provided with two contact portions spaced apart by a predetermined distance in a direction of a relative rotation with respect to the other rotor, and the other rotor is provided with a moving portion that moves between the two contact portions in association with a relative rotation with respect to the releasing body, the moving portion allowing the releasing body to rotate to the first and second rotating positions with respect to the either one of the rotors by touching the two contact portions, respectively. Consequently, it is possible to readily achieve rotating mechanism of the releasing body as discussed above.
Still another angle adjusting device of the present invention is characterized in that the axis of rotation is composed of a rivet.
According to the invention, it is arranged such that the axis of rotation that couples the pair of rotors is composed of a rivet. Consequently, the dimension of the entire angle adjusting device in a direction along the axis of rotation can be made compact.
Still another angle adjusting device of the present invention is characterized in that the spring is a spiral spring.
According to the invention, it is arranged such that the spring is a spiral spring. Consequently, the dimension of the entire angle adjusting device in the direction along the axis of rotation can be made more compact. Here, a conical spring made of a wire material, a volute spring made out of a plate material, etc. can be used as the spiral spring.
Still another angle adjusting device of the present invention is characterized in that each of the engaging portions is shaped into a triangle including the counter surface of either rotor where each is provided when seen on a cross section in a radius direction of a rotation of the rotor, and either one of side portions of the triangle other than a side on the counter surface of either rotor engages with a corresponding side portion of the engaging portion on the other rotor.
According to the invention, it is arranged such that each of the engaging portions is shaped into a triangle including the counter surface of either rotor where each is provided when seen on a cross section in a radius direction of a rotation of the rotor, and either one of side portions of the triangle other than a side on the counter surface of either rotor engages with a corresponding side portion of the engaging portion on the other opposing rotor. Consequently, it is possible to shape each engaging portion into a quite simple triangle tooth.
Still another angle, adjusting device of the present invention is characterized in that the either one of side portions is titled by a predetermined angle toward an engaging direction from the opposing direction.
According to the invention, the either one of side portions is shaped into a serration by giving a tilt of a predetermined angle toward an engaging direction from the opposing direction. Hence, when a force is applied in a direction of a relative rotation of the rotors to maintain their engagement, in order to release the engagement by moving the rotors apart from each other, it is necessary to separate the rotors from each other by forcing each rotor to rotate relatively in a direction against the above force. Consequently, it is possible to maintain the engagement so as not to be released accidentally.
Still another angle adjusting device of the present invention is characterized in that each of the engaging portions is formed by cutting and bending a part of either rotor where each is provided.
According to the invention, it is arranged such that each of the engaging portions is formed by cutting and bending a part of the rotor. Consequently, it is possible to readily form the engaging portions as an integral part of the rotor commonly formed out of a metal plate.
Still another angle adjusting device of the present invention is characterized in that the plurality of engaging portions are aligned in more than one line at different positions in a diameter direction of each rotor where the plurality of engaging portions are provided.
According to the invention, it is arranged such that the engaging portions are aligned in more than one line at different positions in a diameter direction of the rotor. Consequently, because a larger number of engaging portions can be provided, the adjustment can be carried out step by step with a smaller angle.
Still another angle adjusting device of the present invention is characterized in that different intervals are given to the plurality of engaging portions in a direction of a rotation between the pair of rotors opposing each other.
According to the invention, it is arranged such that different intervals are given to the engaging portions in a circumferential direction of a rotation between the pair of rotors. Consequently, even when fewer engaging portions are provided, it is possible to carry out the adjustment in every angle set according to the greatest common divisor of isometric angles of the engaging portions on each rotor.
Still another angle adjusting device of the present invention is characterized in that at least one of the pair of rotors is provided with a coupling portion for coupling to a bar-wise or tube-wise member.
According to the invention, it is arranged such that at least one of the pair of rotors is provided with a coupling portion for coupling to a bar-wise or tube-wise member. Consequently, the coupling portion can be readily coupled to the frames of a legless chair, a foldable bed, for example.
Still another angle adjusting device of the present invention is characterized in that the coupling portion is cylindrical.
According to the invention, because it is arranged such that the coupling portion is cylindrical, the coupling portion can be coupled to the frames more readily by fitting the former into the latter.
Still another angle adjusting device of the present invention is characterized in that at least one of the pair of rotors is formed as an integral part of the coupling portion.
According to the invention, it is arranged such that at least one of the pair of rotors is formed as an integral part of the coupling portion. Consequently, the angle adjusting device can be assembled at a low cost by making these components out of a plate of metal, for example.
Still another angle adjusting device of the present invention is characterized in that at least one of the pair of rotors and the plurality of engaging portions are formed out of synthetic resin as one body.
According to the invention, because it is arranged such that the rotor and engaging portions are formed out of synthetic resin as one body, the angle adjusting device can be assembled at a lower cost.
Still another angle adjusting device of the present invention is characterized in that at least one of the pair of rotors is provided with a cover that covers, either partially or entirely, the plurality of engaging portions from an outside in a radius direction of a rotation.
According to the invention, it is arranged such that at least one of the pair of rotors is provided with a cover that covers the engaging portions from an outside in a radius direction of a rotation. Consequently, it is possible to prevent unwanted intrusion of dust into the engaging surfaces of the engaging portions or the like from the outside.
A further angle adjusting device of the present invention is characterized in that at least one of the pair of rotors and the cover are formed as one body.
According to the invention, it is arranged such that the aforementioned cover and at least one of the pair of rotors are formed as one body. Consequently, it is possible to assemble an angle adjusting device equipped with such a cover at a lower cost.